Many types of equipment are now controlled by computers or microprocessors, either incorporated into the equipment or as separate, freestanding controller units. Examples include manufacturing or processing equipment, computer-aided design (CAD) workstations, home computers, entertainment devices such as audio and video players, and game consoles. A common means for interaction is through the use of a software-controlled graphical user interface (GUI) in which the user sees symbolic representations of commands, hardware or software objects, functions, and portions of the equipment. A well-designed GUI can aid in the efficient, intuitive operation of the equipment. Interaction with a GUI requires an input device that the user can manipulate in order to move an on-screen pointer (“cursor”) or highlighted area on a graphics display screen. This type of input device is called a cursor control device or pointing device, and it is commonly used either in addition to a conventional text-based input keyboard or by itself.
A wide variety of pointing devices for computer input have been developed to meet different needs. Common needs include comfort during use, precision and speed of cursor placement or motion, and relatively compact size. However, specialized needs and deficiencies in the existing devices have led to the continual invention and development of new cursor control devices optimized for different applications. Examples of factors driving innovation in cursor control devices include the following: enhanced intuitive operation for different applications such as drawing or CAD; convenience for use while standing and giving projected presentations; portability or small size for use with or incorporated into portable or handheld computing devices; the desire for a device that uses a relatively small work area on a desk; accuracy in small motions or speed for large motions; enhanced ergonomic qualities to minimize repetitive stress injury (RSI) and improve user comfort; high reliability in adverse environments; and personal preference. There remains a need for novel cursor control devices that are versatile enough to perform well in a larger combination of the above factors and/or that are specialized to perform particularly well for a specific application.
Most cursor control devices rely on visual feedback of cursor position to the user via the display screen, and they are thus relatively tolerant of motion errors, which are quickly compensated by the user. The most popular variations are the “mouse,” a handheld device that is moved relative to a work surface such as the desk, and the “trackball” or “tracker ball,” which is much like an inverted version of an optomechanical mouse. The original mouse design used a trapped ball that imparted rotary motion in x and y to rollers coupled to optical shaft encoders, and this is also the way most trackballs work.
A major deficiency of the mouse is that it needs to be grasped in the hand, and this often leads to muscular fatigue. One size and shape does not optimally fit all users. It requires considerable work surface area to be used, and can fall off of tilted or slippery work surfaces. Optomechanical mice have considerable problems with dirt getting into the mechanism.
Trackballs, which also come in a variety of sizes, have some advantages over mice. They take relatively little desk or panel area. More users find the same size trackball easy to get accustomed to, since it does not need to be grasped. Disabled users who lack grasping ability can operate a trackball. Versions are available that have seal rings around the ball to keep out moisture and dirt. Ruggedized trackballs are thus common on manufacturing and medical equipment and in other locations receiving heavy use such as CAD stations. They can often be operated while wearing gloves.
Advancements in low-cost CMOS image sensors and digital signal processing have been applied recently both to the implementation of optical mice and to the sensing of the motion of trackballs. Examples of prior art assemblies used to construct an optical mouse that tracks work surface features are shown in FIGS. 1 and 2. Components useful in implementing such a mouse are commercially available from vendors such as Agilent Technologies. In use, illumination from a light source hits the work surface at a grazing angle to highlight irregularities with shadows, so that the work surface need not have contrasting features to track. A short focal length lens relays a unity magnification image of the work surface onto the image sensor, which has a small array (e.g., 16×16) of photodetectors in an area approximately 1 mm square. The image sensor has image processing hardware that analyzes sequential frames for motion and outputs cursor-motion signals compatible with standard mouse interfaces. Optical mice using this configuration, while having no moving parts, typically are unsealed, using an open hole for optical interface with the work surface instead of a transparent window.
Trackballs are also available using similar motion-tracking electronic imaging technology to sense patterns on the ball. However, although they use modern optical technology, there is still a ball, as well as other moving parts, and hence potential for contamination with dust and liquids, leading to questionable reliability in industrial applications.
There thus remains an unmet need for an improved cursor control device for industrial and other applications, that provides some of the “feel” of a trackball, but with no moving parts required to change the cursor position, that is designed to be capable of operation using much of the whole hand, that can track a variety of surfaces such as gloves, that is compact in size and suitable for mounting in a panel, and that is capable of being substantially sealed from the environment.
When choosing a cursor control device, there are certain desirable characteristics that may be more or less important depending on the particular application. Following is a non-comprehensive list of areas of potential improvement for cursor control devices. While these features are particularly useful in cursor control devices for use in industrial control applications, it should be noted that such features will also be considered desirable in many other applications.
Reliability: no moving parts; sealed enclosure; capable of being constructed from environmentally-resistant materials (chemical, abrasive, cleanable).
Convenience and versatility of installation and operation: capability of panel mounting; compact size; operation in any orientation or position; operation in high-vibration environments; operation in high g-force environments; potential for different visual designs.
Ergonomics: intuitive operation; visual and tactile indication of operation; capable of operation with whole hand and/or arm motion; optimum mounting position and orientation; use with relaxed hand, arm, and fingers, with no grasping for reduced danger of repetitive stress injury; usable by disabled individuals.
Aesthetics: interesting, attractive appearance; potential for different visual design styles and colors; looks “cool” or “high-tech.”